Island



G. P. GERFIN AND M. MAURAN. PROCESS 0F FORMING A MIXTURE 0F HYDROGEN AND NITROGEN FOR AMMONIA SYNTHESIS.

APPLICMION FILED NOV. l5

` Patented Aug. 17,1920. I

. s Ann: x Env INVENTORS ATTORNEY Y UNITED sTArns eATeNT FFEEEL.

GEORGE I'. GERFIN AND MAX MAURAN, OF NIAGARA FALLS, NEW YORK, ASSIGNORS TO THE NITROGEN GORPORTION,l OF PROVIDENCE, RHODE ISLAND, A COR-PURA- TIOIN OF RHODE ISLAND.

Specification of Letters Patent.

or HYDROGEN AND NITROGEN Foa AMMONI'A SYNTHESIS. l

rammed Aug. 1v, 1920.

Application filed November 15, 1318. Serial No. 262,716.

To all imitant 'it 'may concern:

15e it known that we, Grenen P. GERFIN and hln; MAUnaN, citizens of the United States, residing `at Niagara Falls, in the county of Niagara and State of New York, have invented certain new and useful lmproveinents in Processes of Forming a Mixture of i'lydrogen and Nitrogen for Ammonia Synthesis, of which the following is a specification. i

This invention relates to a method of and leans for formino' `a-1ni:\ture`of hydrogen and nitrogen suitable for use in ammonia synthesis, and liasjfor one of its objects the elimination of much of the costly and cumbersome apparatus heretofore employed to this end in attempted commercial operations, while at the same time reducing the number of steps or operations in-such a process, substantially to a minimum.

This and other objects of our invention will be hereinafter referred to and the novel combina tion of steps in` our improved process, and of'ineans znideleinents whereby said process may be Inost simply and expeditiously effected, will be morev particularly pointed `out in the claims appended '(flaiiiis, brozully interpreted inthe light o our disclosure. ln the drawing, which formsa part hereot', we have exemplified a preferred embodiment of the apparatus in which' our said process may be effectuated. l

iefcrriug to said drawing, in which like reference characters designate like parts in the respective views:

Figure l is a diagrammatic representation of a system through the instrumentality of which. a mixture of substantially pure nitrogen and hydrogen in combining proportions may ble-produced. i i Fig. is a'detail, partly in section, shOwing the construction of the burner or blast lam D. Y

The receptacle l, represents a tank or reservoir of air under pressure; this reeep tafle therefore constituting a source of air, and the pressure of the latter being conpreferably preheated hydrogen. The hydrogen is supplied from a pipe t, in which is a controlling valve t', and passes thence through a preheating chamber 5 in the burner illustrated in Fig. 2, before it enters the mining conduit 3, via pipe 3.

The hydrogen is also preferably under a pressure of, for example, 25 `or 30 pounds; the press ureiof the resulting mixture in pipe il, ho'uf'ever, being materially less on account of the loss of pressure in the burner.

T his burner, which preferably comprises two iron heads (i, provided with stuffing bones 7--7 and with refractory tubes 8-8 therebetween, receives the hydrogen from pipe t, preheats it, and subsequentlyv receives within the tube 8, the mixture of preheated hydrogen and air from Vpipe 3; the combustion products, formed in said tube 8 as hereinafter described, passing from the burner through a pipe 9 to a condenser l0. The construction of the burner, which is important, will be hereinafter considered in more detail. A preferably upwardly extending short tube or pipe 1l, provided witha valve or cock l2, serves as a convenient and simple `nieansto effect the ignition of the gases in tube 8; while a similar downwardly directed pipeY 13, with its pet-cock or valve 14;, affords a means to-ascertain whether proper combustion conditions have been established. Y

r The tubeV 8, in which combustion of the hydrogentowater is effected, is desirably of substantially pure drawn silica or like very highly refractory material which is incapable ofL deleteriously affecting the product; it being,rof course, necessary to avoid using refractory material in the exposed inner wall of this tube, which could Vin any'way'cont'aminate the gaseous product, as by yielding oxygen, sulfur or the like, thereto. The condenser preferably comprises a cas ing in which is a coil 10 throughV which cooling water is passed to condense the water present in theV gases leaving the burner.`

Both the gases andcondensed water leave the condenser via pipe l5; the water draining ofi" through pipe 16 into an air tight tank 17, or the like, while .the gases pass through pipe 18 to a gasometer 19 or other suitable receptacle.

The latter is connected by a pipe 20, preferably, with a compression pump 2l which delivers the gaseous mixture, under pressure, to a storage tank 22, whence the gases are caused to {low at the `rate and in the manner desired through a pipe 24 to a suitable purifying apparatus 25 containing provisions for removing any remaining traces of water, oxygen or the like. As the details of the purifying apparatus, per se, form. no part of the present invention and since the use of soda-lime and like absorbents for water vapor and other impurities, is well known, this apparatus need not herein be further described.

The flow of gas through thepurifying apparatus is. controlled by the valve 24 in pipe and this gas, or gasenls mixture, is l'n'cferably, although not necessarily, at such time under a pressuie of about 150 pounds per square inch; the pump 2l delivering gas under this pressure to the tank 22.

The gases emerging from the apparatus 25, through thev pipe 26, are now ready for use.

If it be desired to effect the synthesizing operation at a higher pressure than l() atmpheres, as in some cases is to be preferr-ed, this increase in pressure may be attained in a known fashion; care being taken to avoid the introduction of impurities into the material from which the ammonia is to be produced.

Before discussing the process, we shall now consider the construction of the burner in more detail. Referring to Fig. 2, it Will be observed that the heads 6 are connected by tie-rods 27, which are provided with nuts, 27, to also serve as spacers. The heads and these rods, hence, together constitute a frame.

The heads are provided with glands 28 which receive the ends of the combustion shell or tube 8, and co-act with the stuffing boxes 7 to e'ect gas tight joints by means of packings 29', bolts 30 permitting these boxes to be packed as tightly as necessary. y

The respective ends of the screening shell S', which forms the outer wall of the preheating chamber 5, are similarly received into annular glands 31 on the heads 6, and the stuffing boxes 7 similarly co-act -With these preferably beveled extensions or glands, to enable the packings 32 to seal the ends of the screening shell.

The heads 6 are interiorly recessed, as at 33, to respectively permit ingress and egress of the hydrogen, from and to the ports 34,

which communicate with the pipes 4 and 3', as shown.

Aside from effecting gas tight joints, a great advantage resides in thus mounting in packing the ends of the refractory tubes, since expansion and contraction of these latter with respect to thc 1 )2'eierably rigid frame is thereby possible without risk of injury to the tubes or of the development of leaks.

The mixing tube 3, is preferably threaded into one of the glands 28, While the pipe 9 is similarly connected to the other gland 28. lVith the exception of the provision of a burner, proper, or nozzle 35, which may conveniently be formed as an integral extension of the mixing pipe- 3, the burner is preferably the same at both ends.

The tip of the nozzle 35, where the hydrogen and air are ignited, is located at a sufli cient distance fmm the cast iron head, to avoid unduly heating this latter.

As above intimated, the present invention is particularly concerned with the production, in an exceedingly simple manner, of a mixture of pure nitrogen and hydrogen in combining proportions and under any de sired pressure, substantially ready for use in an ammonia synthesizing operation, and the process of effectuating said production in the apparatus given by way of exemplification, will now be briefly described.

Substantially pure hydrogen, preferably under pressure, is supplied via pipe 4 to the annular space between the concentric tubes Sw,v which constitutes the prcheating chamber As the tube 8 is highly heated by the exotl'rermie reaction effected therewithin, the hydrogen passing through the somewhat constricted chamber 5, becomes highly preheated, in part by direct radiation from, and in part by direct contact with, the tube 8. It is then mixed with air under a like pressure from the tank l or its equivalent; the valves 2' and et being set to admit definitely related quantities of air and hydrogen to the mixing pipe 3, so that not only shall the oxygen of the admitted air be combined with hydrogen in the burner, to form water; but, further, that after such combination has been effected there shall then be present in the gases entering pipe 9, a mixture of three parts, by volume, of hydrogen to one of nitrogen.

In starting the operation, the cock l2 is opened to permit of egress of some of the mixture through pipe ll, and the emerging gases are preferably, at once ignited. The flame flashes back into the burner and effective combustion in the manner indicated ensues practically immediately; perfect combustion being attained as soon as the silicious inner tube 8 becomes heated to a bright red, which it normally speedih7 does.

The cock l2 is, of course, closed as soon as the gases have been ignited and the cock lllinay then be opened to ascertain if water, or rather steam, is being formed as it ought to be; after which this test cock should also be closed.

The steam present in the pipe 9 is con- Verted into water'in the, condenser l0, and

flows via pipes l5 and 1G into the tank 17 about .150 to 200 pounds per square inch and the compressed gas is thereafter permitted to flow through suitable purifying apparatus 25, to eliminate any traces of water, oxygen or other deleterious impuri-V ties. Y

The mixture of gases supplied to the burner and the resulting change therein may be aivipi'oxiinately represented by the 'following equation,` in which for simplicity, the air is assumed to consist of one part of oxygen to four of nitrogen:

That is to say, approximately one seventh of the hydrogen supplied is consumed in converting the oxygen of the air into water; or in other words, the hydrogen is about 600% in excess of the amount thereof required to consume all of the oxygen present ina given volume of air.

The resultant gaseous mixture in such case contains nitrogen and hydrogen in eoii'il' iniiig` proportions, together' with rthe water formed and, of course, the argon and other gases, xenon, ltrypton, neon, etc., initially present ii'iY the air. As the argon and rare atmospheric elementary gases are inert, their presence in the gaseous `product is unobjectionable; but the water formed, together with any carbon dioxid, traces of oxygen, or like impurities present, must be removed.

l consider it desirable to effect the removal of such `impurities after the gaseous mixture has been stepped up tothe given or desired pressure of, say, 150 or more pounds per square inch; since this permits of the use of purifying apparatus of less `volume than is apt to be required where substantially uncompressed gas is treated. Further, the rate of flow of the gaseous mixture through the treating or purifying materialv in appa 'atus 25, `is of course less,

proportionately, when the gas is highly Ycompressed than when it is not; while l'iighly compressed gas may be eilicaciously purified more readily than gas at but one or two atmospheres pressure, probably because more of the inoleculesof the gas are driven intimately into contact with the purifying material in a given time, especially when the purifying material is yin solid form, like 'fragments of soda-lime, or the like. f

l also prefer to effect purification of the l gas shortly after it has been placed under a materially increased pressure; because at such time its temperature normally is higher and the reaction of the purifying material or materials upon any impurities present, is hence more vifforous.

ln this connection, also, it may bewellto note that it is of material advantage vto supply the air andV hydrogen to the burner, under pressure, as described, since4 this enables the obtaiinnent ofa fairly even rate of flow of the gases through the usualregulating devices. The principal reason, for

maintaining the hydrogen and air under approximately equal pressures, is, correspondingly, to enable the regulating valves 2 and 4l to be properly adjusted with facility.

In effecting the combustion, the excess hydrogen behaves, in effect, as an inert diluent; because there isonly a vrelatively small quantity of oxygen present, per unit of volume. The result is that if vthe great tendency to slow down andretard the combustion' of the given limited percentage thereof with the oxygen, and this favors the formation ofV product which includes perceptible traces of uncoinbined or free oxygen. The effectuation of the combus- V10o quantity of hydrogen introduced into the burner is not properly preheated, there is a tion under the prescribed conditions, liow'- Y ever, 'practically eliminates this tendency;

` lWhen said combustion is proceeding favorably, the silicious tube ofthe burner gloiifs brightly red; but evenin spite ofthe relatively high 'temperature thereby indicated, traces of i'incombined oxygen may escape into the tube 9, if, for example, the

tube 8'.' or an equivalent screen, be not propreheated in any desired manner; but since the air and hydrogen cannot safely be highly preheated together, and since the hydrogen content of the mixture to be formed in tube 3, normally greatly exceeds that oi" the air in said mixture, we have found it best to highly preheat the hydrogen alone, and then to form the preheated mixture simply by the addition of air thereto.

It is because of the necessarily high temperature within the burner tube, which is continuously maintained for long periods of time, that we prefer to construct the shell 8 of some highly heat resistant material such as fused silica or quartz, rather than to make it of iron or the like. Such material can be heat insulated, or otherwise have the required temperature attained therein, without danger of melting the tube or contaminating the product, and this is a feature, the importance of which can scarcely be overestimated.

In other words, a burner tube of material for use in connection with this process, should be adapted to perform a plurality of important functions in that it in large measure should prevent heat losses; it should be gas tight and adapted to withstand the pressure to which it is subjected; it should not ybecome oxidized nor introduce impurities into the product; and it shouldv not fail by reason of the high temperature maiutained therein. Furthermore, it should be so mounted that expansion or contraction thereof cannot cause it or its associated parts to fail; while the connections thereto should be gas tight.

The construction of` a burner, and especially of a gas preheating burner which shall efliciently meet these conditions, and yet be simple and relatively inexpensive, involves complications and difficulties which the preferred type of burner successfully overcomes. In this connection, also, it may be observed that an additional advantage is derived from supplying the gaseous mixture formed in the tube 3, under pressure to the burner proper; sinceV on account of the comparative absence of pressure in the shell 8, as compared to that in tube 3, the gas mixture emerges from the nozzle 35, with sufficient velocity to cause the projection of the flame away from the tip ofthe nozzle, to permit the latter to be made inexpensively of iron, for example, without danger 0f its heilig melted.

If the pressure in pipe 3 be materially increased, then, of course, the combustion chamber, may be operated under pressure, to aid in effecting perfect. combustion; although, operating in the manner described we produce a gaseous mixture which is practically free from oxygen, and, hence, normally, the indicated pressures suiice.

It is by no means essential that the tubes 8 and 8 be made of the same material, because the outer shell is exposed to a much less intense heat than is the shell S; but since the preferred material is translucent, the use of such material for both shells permits of direct observation of the condition of the li ame in the burner.

By means, therefor, of the above process and by the use of relatively inexpensive and simple apparatus, such as that described, we are enabled to produce a mixture of gases from which ammonia may be readily synthesized catalytically; the gaseous mixture comprising substantially pure hydrogen and nitrogen and these gases being in combining proportions.

Finally, it will be understood that by the term water, as used in certain of the claims, such term is to be regarded as of su'tlicient breadth to include water vapor or steam; the use otl said term being desirable to avoid circumlocution.

Having thus described our invention, what we claim is:

l. A process of producing substantially pure, mixed hydrogen and nitrogen which comprises forming a mixture ot air and hydrogen, in which, per unit oi? volume, the hydrogen is present in excess of the amount thereotl which would completely unite with the oxygen content of such volume, in the form of water, causing said mixture to How through a conduit the walls of which are substantially .incapable oi? deleteriously atlecting the product to be formed, igniting said mixture in said conduit and maintaining the temperature of the flame thereby formed, suliciently high to insure substantially complete elimination ot vtree oxygen from the mixture, cooling the r iaction products, separating the water therein 'from the gases present, compressing said gases and purifying thcui prepara-,tory to the ei'l'ectuation of ammonia synthesis therefrom.

2. A process oi producing pure, mixed hydrogen and nitrogen which comprises, eifecting a combination of the oxygen coutent oi a gaseous mixture o hydrogen and air flowing through a conduit, with buta portion oi said hydrogen, the hydrogen present in said mixture being so greatly in excess ot that required for said combination, that for the greater part it behaves as an inert diluent during the cours oi, and tends to retard said combination, and promoting said combination substantially to completion in spite of said retarding actionv` by maintaining the temperature of said conduit at bright red heat.

3. A process of producing pure, mixed hydrogen and nitrogen which comprises, etecting a combination of the oxygen content of a gaseous mixture of hydrogen and air flowing through a conduit, with but a portion ot said hydrogen, the hydrogen present in said mixture being so greatly in excess of that required for said combination, that for the greater part it behaves as an inert dilu- "ent during the course of, and tends to retard said combination, and promoting said combination substantially to completion in spite oi said retarding action, by maintaining the temperature of said conduit at bright red heat While holding saidgaseous mixture under pressure;

1l. A process of producing pure, mixed hydrogen and nitrogen which comprises, es tablishing a continuous flow of a mixture of hydrogen and air, in the itorm or a jet, into a combustion chamber the Walls of which are oi heat insulating material, combining the oxygen content ot' said mixture with a portion et the hydrogencontent thereof, in said chamber, to form steam, cooling the resulting gaseous mixture to condense `said steam to Water after tlieremoval of the mixture from said chambenseparating said water from the gaseous mixture of nitrogen and hydrogen remaining, compressing said mixed nitrogen and hydrogen, and purify-V ingthe saine While compressed.

5. A process of producing pure, mixed hydrogen and nitrogen which comprises establishing a continuous flow of a heated mixture of hydrogen and air in the term of a `jet, into a combustion chamber the Walls oi which are of material which is a poor conductor ot heat, combining the oxygen content ot said mixture with the hydrogen content thereof, in said chamber, to form steam While heating said Walls to a bright red heat, passing the hydrogen which is to be admixed With air to form said mixture, 4

of a gaseous mixture of hydrogen and air flowing through a conduit, with a portion of the hydrogen of said mixture, to lorm steam, While simultaneously imparting a portion of the heat evolved by said combination to one of the gaseous constituents of said mixture to preheat said mixture previous to' the eflectuation of said combination, cooling the resulting gaseous mixture to condense the steam tewater, and separating said 'Water from the gaseous mixture ot nitrogen and hydrogen remaining.

In testimony whereof We have affixed our signatures in the presence of two Witnesses.

GEORGE l). GERFIN. MAX MAURAN.

TWitnesses:

Jol-1N Gr. GENTLEMAN, Y, 1*. BoYNToN BUTLER. 

